KR101911551B1 - Configuration and method of operation of an electrodeposition system for improved process stability and performance - Google Patents

Abstract

A method, system and apparatus for plating a metal on top of a workpiece using a plating solution having a low oxygen concentration are described. In one aspect, the method includes reducing the oxygen concentration of the plating liquid. The plating solution contains about 100 ppm or less of a promoter. After reducing the oxygen concentration of the plating liquid, the wafer substrate is brought into contact with the plating liquid in the plating cell. The oxygen concentration of the plating solution in the plating cell is about 1 ppm or less. The metal is electroplated on the wafer substrate by the plating liquid in the plating cell. After the metal is electroplated onto the wafer substrate, the oxidation strength of the plating liquid is increased.

Description

TECHNICAL FIELD [0001] The present invention relates to an electrodeposition system, and more particularly, to an electrodeposition system for improved process stability and performance.

Cross-reference of related application - reference

This application claims the benefit of U.S. Provisional Application No. 61 / 430,709 filed on January 7, 2011, § 119 (e), which is incorporated herein by reference.

The present invention provides a method, apparatus and system for plating metal.

background

Damascene processing is a method for forming a metal wiring on an integrated circuit. This process is often used because it requires less process steps and provides higher yields than other processes. The conductive path formed on the surface of the integrated circuit during the inlaid process is often filled with copper. Copper may be deposited in a conductive path by an electroplating process using a plating solution.

summary

A method, apparatus and system for plating metal are provided. According to various embodiments, the methods include reducing the concentration of oxygen in the plating liquid, contacting the wafer substrate with the plating liquid, electroplating metal onto the wafer substrate, and oxidizing strength of the plating liquid. .

According to one embodiment, a method of electroplating a metal onto a wafer substrate includes reducing the oxygen concentration of the plating solution, wherein the plating solution comprises about 100 parts per million (ppm) or less of an accelerator. After reducing the oxygen concentration of the plating liquid, the wafer substrate is brought into contact with the plating liquid in a plating cell. The oxygen concentration of the plating liquid in the plating cell is about 1 ppm or less. The metal is electroplated on the wafer substrate by the plating liquid in the plating cell. After plating, the oxidation strength of the plating solution is increased.

According to one embodiment, an apparatus for electroplating a metal includes a plating cell, a degassing apparatus, an oxidation station, and a controller. The plating cell is configured to hold the plating liquid. The degassing apparatus is connected to the plating cell and is configured to remove oxygen from the plating liquid before the plating liquid flows into the plating cell. The oxidation station is connected to the plating cell and the oxidation station is configured to increase the oxidation strength of the plating liquid after the plating liquid flows out of the plating cell. The controller includes a program instruction for managing the process including the operation of reducing the oxygen concentration of the plating liquid using the degassing apparatus. The plating solution contains about 100 ppm or less of a promoter. After the degassing step, the wafer substrate is brought into contact with the plating liquid in the plating cell. The oxygen concentration of the plating solution in the plating cell is about 1 ppm or less. The metal is electroplated on the wafer substrate by the plating liquid in the plating cell. After electroplating, the oxidation strength of the plating liquid is increased using an oxidation station.

According to one embodiment, a non-volatile computer-readable medium comprising program instructions for controlling a deposition apparatus includes a code for reducing the oxygen concentration of the plating liquid. The plating solution may contain about 100 ppm or less of a promoter. After reducing the oxygen concentration of the plating liquid, the wafer substrate is brought into contact with the plating liquid in the plating cell. The oxygen concentration of the plating liquid in the plating cell is about 1 ppm or less. The metal is electroplated on the wafer substrate by the plating liquid in the plating cell. After plating, the oxidation strength of the plating solution is increased.

These and other aspects of embodiments of the invention described herein are set forth in the following drawings and description.

A method, system and apparatus for plating a metal on top of a workpiece using a plating solution having a low oxygen concentration are described.

Brief Description of Drawings
Fig. 1 shows an example of a method of electroplating a metal onto a wafer substrate.
Figure 2A shows an example of a schematic diagram of an apparatus configured to carry out the method described in the present invention.
Figure 2B shows an example of a schematic view of the reservoir.
Figure 3 shows an example of a schematic diagram of an electrofill system.

details

In general, the embodiment described in the present invention provides an apparatus and a method for controlling the plating liquid composition.

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. It will be apparent, however, to one of ordinary skill in the art that the disclosed embodiments may be practiced without these specific details, or may be practiced with alternative elements or processes. In other embodiments, well-known processes, processes, and components are not described in order to avoid unnecessarily obscuring aspects of the practice of the invention.

In the present application, the terms "semiconductor wafer", "wafer", "substrate", "wafer substrate", and "partially fabricated integrated circuit" are used interchangeably. Those of ordinary skill in the art will understand that the term "partially fabricated integrated circuit" means a silicon wafer during various stages of integrated circuit fabrication. The following description assumes that the disclosed embodiment is performed on a wafer substrate. However, the disclosed embodiments are not limiting. The work piece can be of various shapes, sizes, and materials. In addition to semiconductor wafers, other work materials that may utilize the disclosed embodiments include various articles such as, for example, printed circuit boards.

An embodiment of various aspects described in the present invention relates to a method for controlling the gas concentration in a plating solution and the oxidation intensity of a plating solution. This method can be achieved by separate mechanisms used at specific locations of the plating solution flow passage in the plating apparatus. For example, the implementation of the method includes (a) degassing the plating liquid prior to introducing the plating liquid into the plating cell, and (b) increasing the oxidation strength of the plating liquid at a downstream point of the plating cell can do. The oxidation strength of the plating solution can be increased to a level that promotes or maintains the formation of the desired oxidation state of the plating additive (e. G., The disulfide form of the promoter). Degasing the plating liquid in contact with the wafer substrate to deposit metal on top of the wafer substrate can help reduce corrosion of the seed layer on the wafer substrate and dissolve small air bubbles on the wafer substrate. The degassing of the plating solution also prevents the oxidative breakdown of the additives in the plating solution, especially the promoter, thereby reducing the use of the additive and reducing the formation of harmful by-products of the additive, enabling a longer plating solution life . This is particularly true when the degassing is combined with the plating cell in which the plating liquid has a separate anode chamber so that oxidation of the additive on the anode is also prevented. Electroplating apparatuses having separate anode chambers are disclosed in U.S. Patent No. 6,527,920 and U.S. Patent No. 6,821,407, both of which are incorporated herein by reference.

However, if the plating solution is maintained at an oxygen concentration of about 0.1 ppm to 1 ppm, normal oxidation of the accelerator reduced in the wafer substrate during plating is prevented as described below. This promptly causes depolarization of the plating liquid and loss of the filling ability of the plating liquid. In order to overcome this problem, and according to various embodiments described in the present invention, it is possible to increase the oxidation strength of the plating solution after plating the metal on the wafer substrate.

Introduction

The plating solution may contain various additives, including promoters, inhibitors, and levelers. Accelerators, in other words brighteners, are additives that increase the rate of the plating reaction. Accelerators are molecules that adsorb on metal surfaces and increase the local current density at a given applied voltage. The promoter may contain a pendant sulfur atom, which is understood to participate in the copper ion reduction reaction and have a strong influence on the nucleation and surface growth of the metal film. The accelerator additive is typically a derivative of mercaptopropane sulfonic acid (MPS), dimercaptopropane sulfonic acid (DPS), or bis (3-sulfopropyl) disulfide (SPS), and other compounds may be used. Non-limiting examples of deposition promoters include: 2-mercaptoethanesulfonic acid (MESA), 3-mercapto-2-propanesulfonic acid (MPSA), dimercaptopropionesulfonic acid (DMPSA) Mercaptoethanesulfonic acid (DMESA), 3-mercaptopropionic acid, mercaptocarbazole, 3-mercapto-2-butanol, and 1-thioglycerol. Some useful accelerators are disclosed, for example, in U.S. Pat. No. 5,252,196, which is incorporated herein by reference. Accelerators include, for example, Ultrafil A-2001 from Shipley (Marlborough, Mass.) Or SC Primary from Enthone Inc. (West Haven, Conn.).

In other words, the carrier is a polymer that tends to suppress current after adsorbing to the metal surface. The inhibitor may be derived from polyethylene glycol (PEG), polypropylene glycol (PPG), polyethylene oxide, or derivatives or co-polymers thereof. Commercial inhibitors include, for example, Ultrafill S-2001 and Enthone Inc. of Shipley (Marlborough, MA). (West Haven, Conn.).

Levelers are generally cationic surfactants and dyes, which inhibit the current in the region where their mass transfer rate is highest. Thus, the presence of the leveler in the plating liquid serves to reduce the film growth rate at the protruding surface or corner where the leveler is preferentially absorbed. The difference in leveler absorption due to different mass transfer effects has a significant impact. Some useful levelers are disclosed, for example, in U.S. Patent Nos. 5,252,196, 4,555,135 and 3,956,120, which are incorporated herein by reference. Levelers are available from Shipley (Marlborough, Mass.) As a Liberty or Ultrafill Leveler, and from Enthone Inc. as Booster 3, for example. (West Haven, Conn.). Accelerators, inhibitors, and Vellers are further described in U.S. Patent 6,793,796, which is incorporated by reference.

Copper electroplating to a conventional wafer substrate is performed, for example, using a plating solution that can contain dissolved oxygen in an amount of about 8 ppm to about 10 ppm dissolved nitrogen and a higher amount of dissolved nitrogen in equilibrium with air. This can lead to at least three different situations. First, when the plating solution passes through the high pressure pump to transfer the plating solution to the wafer substrate, the pressure change experienced by the plating solution may cause air bubbles to condense from the solution in the low pressure region between the pump and the wafer substrate. These air bubbles can cause electroplating defects by seating and attaching on the wafer substrate or by accumulating in or on the plating cell element located below the wafer substrate and by changing the electroplated profile and the obtained plated thickness distribution on the wafer substrate have.

Second, the copper seed layer in small features on the wafer substrate is often a very thin and almost discontinuous spot. Dissolution of the seed layer in the plating liquid prior to nucleation may cause lack of seed layer and thus cause voids in the plated metal to fill the feature. Dissolution of the seed layer can occur because oxygen in the plating solution can oxidize copper at a rate of about 1 nanometer per minute.

Third, the additive in the plating solution may react with oxidation to form a by-product, which may deteriorate the plating solution performance or require replacement or treatment of the plating solution more frequently. For example, promoter additives used in copper plating solutions, including SPS, DPS, related mercapto-containing species, and by-products of such compounds, are known to be sensitive to the oxygen concentration of the plating solution. See, for example, Reid, J. D., "An HPLC Study of Acid Copper Bleaching Properties," Printed Circuit Fabrication, (Nov. 1987), pp. 65-75, which is incorporated by reference. Although the byproducts formed are not fully known, the SPS initially added to the plating solution can be converted from the wafer substrate to the monomeric MPS in the reduction reaction. Oxidation by contact with oxygen or anodes in the plating solution can convert the MPS back to SPS. SPS and MPS are kept in equilibrium in the plating solution. Therefore, from this viewpoint, some oxygen in the plating liquid is useful. However, MPS can also be further irreversibly oxidized (i.e., form oxidized mercaptopropane sulfonic acid (MPSO)) to the chemical species at the anode or by air, which is not readily re-converted to SPS. When these chemical species begin to form, the total use of the accelerator additive increases and the overall volume of by-product in the plating solution may increase. As byproducts often degrade the plating solution, treatment of the plating solution to remove by-products or to remove the replenishment of the plating solution may be essential. All of these options are costly.

Degassing the copper plating solution can help overcome some of the problems described above. For example, with respect to the first problem, when a gas containing molecular oxygen and molecular nitrogen is displaced from the plating liquid, and thus the plating liquid is not saturated by air, small air bubbles spontaneously and more rapidly dissolve in the plating liquid will be. When the wafer substrate enters the plating liquid, the plating liquid can wet the copper surface and gradually replace the surface of the wafer substrate and the air in the features. However, entering the wafer substrate into the plating liquid can cause air bubbles to be generated, and the air bubbles can adhere to the wafer surface and prevent plating, thereby causing missing metal defects (pits) Therefore, rapid dissolution of air bubbles in the plating liquid can be advantageous. The rate of air dissolution in the unsaturated solution may be about 1.2 x 10 ^-6 g / cm ² -sec, which results in rapid removal of small air bubbles (e.g., removal of 10 micrometer air for about one second). For example, about 4 times (4x) pit-type defect reduction was observed at the copper seed surface when using a degassed plating solution as compared to a non-degassed plating solution.

In connection with the second problem, reducing the oxygen concentration in the plating liquid by degassing the plating liquid can cause a low corrosion rate of the copper seed layer when first deposited in the wafer-based pi-plating solution. For example, when the oxygen concentration in the plating solution was reduced from about 8 ppm to 0.5 ppm, about 50% reduction in copper seed layer corrosion rate was observed.

In connection with the third problem, it has been observed that reducing the oxygen concentration in the plating solution reduces the use of additives and also reduces the formation of additive byproducts. For example, it has been observed that the stability of the promoter in the plating liquid improves by a factor of about 2 when the plating liquid is deaerated to remove oxygen and the anode is isolated from the plating liquid, so that the promoter is not in contact with the anode. This is because the collapse of the irreversible decomposition of MPS (for example, when SPS is an accelerator) into a byproduct is suppressed.

However, as described above, reducing the oxygen concentration in the plating liquid can disrupt the equilibrium of the chemical species constituting the promoter and the promoter. For example, for a plating solution containing SPS as an accelerator, the degassing of the plating solution hinders re-equilibration of the MPS formed when plating the SPS, and the performance of the plating solution can be rapidly deteriorated.

More generally, some organic disulfide type promoters can be maintained in equilibrium with the mercaptan compound in the plating solution. If the plating solution is too much reduced (can be released if it is deoxidized), equilibrium prefers the formation of a less oxidized form of the promoter (e.g., in the form of mercaptans). This provides an undesirable plating state (e.g., the plating liquid can be polarized too much).

Thus, to solve this third problem, it is desirable to increase the oxidation strength of the plating liquid (e.g., by re-introducing oxygen into the plating liquid) prior to pumping the plating liquid to the wafer substrate and degassing it to form the SPS-MPS re- And for plating liquid polarization and filling. For example, the plating liquid in the plating cell may contain a very low gas concentration (e.g., at least a saturation concentration). Elsewhere in the plating system comprising the plating cell, the plating liquid may have an oxidation strength such that the plating liquid additive, such as an accelerator, is maintained in a suitably active state. Increasing the oxidation strength of the plating liquid outside the plating cell can move the equilibrium to the desired form of promoter.

In short, the concentration of oxygen in the plating solution for preventing the seed corrosion and preventing decomposition of the promoter may be as close to zero as possible. The concentration of all the dissolved gas in the plating solution for dissolving air bubbles may be as close to zero as possible. However, because of the differentiation of the MPS-SPS equilibrium and the promoting properties of these two molecules, the concentration of oxygen in the plating solution for the promoter effect on the filling performance behavior in the plating system may be about 1 ppm oxygen or more. To address this contradictory goal, the method and apparatus can be designed such that the wafer substrate is treated at a low gas concentration while the time-averaged concentration of oxygen or other oxidizing species in the plating solution is about 1 ppm. Thus, the plating liquid properties that produce a bottom-up fill in the features on the wafer substrate are maintained while the stability of the plating liquid is improved (i. E., Accelerator decomposition is prevented).

For example, in some embodiments, a degasser may be placed in front of the plating cell so that the plating liquid in contact with the wafer substrate has an oxygen concentration in the range of about 0.1 ppm to 1 ppm, It can be re-equilibrated with the chemical species or air so that the desired MPS-SPS recycling can yield good filling performance. The method and apparatus combine plating liquid conditions that provide a plating gas with a low gas and / or oxygen concentration plating solution while preventing poor filling of the features in the wafer substrate.

Way

The copper electroplating may use a plating solution containing a copper salt such as copper sulfate (CuSO ₄ ), an acid of an acid, and various plating solution additives to increase the conductivity of the plating solution. The plating liquid additive generally exists at low concentrations (about 10 ppb (parts per billion) to 1000 ppm) and affects the surface electrodeposition reaction. In general, additives include promoters, inhibitors, levelers, and halides (chloride ions and bromide ions, for example), each of which has a unique and beneficial role in the production of copper films with the desired micro and macro characteristics .

In some embodiments, the concentration of copper ions from the copper salt is from about 20 g / L to about 60 g / L. In some embodiments, the concentration of the accelerator is from about 5 ppm to 100 ppm and the concentration of the leveler is from about 2 ppm to 30 ppm. In some embodiments, both contain an inhibitor concentration of about 50 ppm to 500 ppm. In some embodiments, the plating liquid may further comprise an acid and a chloride ion. In some embodiments, the concentration of acid is from about 5 g / L to 200 g / L and the concentration of chloride ion is from about 20 g / L to 80 mg / L. In some embodiments, the acid is sulfuric acid. In some other embodiments, the acid is methanesulfonic acid.

In some embodiments, the plating liquid may comprise copper sulfate, sulfuric acid, chloride ions, and organic additives. In such embodiments, the plating solution may contain copper ions at a concentration of from about 0.5 g / L to 80 g / L, from about 5 g / L to 60 g / L, or from about 18 g / L to 55 g / L to 400 g / L sulfuric acid. The low-acid plating solution typically contains about 5 g / L to 10 g / L sulfuric acid. The intermediate and high-acid plating solutions each contain sulfuric acid at a concentration of about 50 g / L to 90 g / L and 150 g / L to 180 g / L, respectively. The chloride ion may be present at a concentration ranging from about 1 g / L to 100 mg / L.

In certain embodiments, the plating solution is a plating solution sold under the tradename DVF 200 ^TM (Enthone Inc.), which is a copper methanesulfonate / methanesulfonic acid plating solution with an accelerator, inhibitor, leveler additive, and 50 ppm chloride ion added.

Fig. 1 shows an example of a method of electroplating a metal onto a wafer substrate. The method 100 begins at block 102 to reduce the oxygen concentration in the plating liquid. For example, the oxygen concentration in the plating liquid can be reduced by degassing the plating liquid. The oxygen concentration in the plating solution may be about 8 ppm to 10 ppm, depending on the atmospheric pressure, due to oxygen in the atmosphere. In some embodiments, the plating liquid is degassed immediately prior to introduction into the plating cell, while in some embodiments, the plating liquid is degassed in the plating cell. For example, the plating liquid can be degassed by flowing the plating liquid through the degassing unit.

Another method for reducing the oxygen concentration in the plating solution includes sparging. Sparging is a technique that removes dissolved gas from a liquid by creating a chemically inert gas droplet through the liquid. For example, helium can be injected into the plating liquid to replace oxygen and nitrogen, or nitrogen can be injected to selectively replace oxygen. Reducing the oxygen concentration in the plating solution may be accomplished by using a membrane for saturation rather than removing the gas from the solution, or by operating the process tool in near-vacuum conditions coupled with selective gas introduction . For a discussion of various degassing techniques, reference is made to US patent application 12 / 684,792, filed January 11, 2010, which is incorporated by reference.

At block 104, the wafer substrate is brought into contact with the plating liquid in the plating cell. In some embodiments, the oxygen concentration of the plating liquid in the plating cell is about 1 ppm or less. For example, the oxygen concentration of the plating liquid in the plating cell may be about 0.1 ppm to 1 ppm.

At block 106, metal is electroplated onto the wafer substrate in the plating cell. Electrical power, which may be provided from the control current and / or potential, is applied to the wafer substrate to deposit the metal.

At block 108, the oxidation strength of the plating liquid is increased. The oxidation strength of the plating liquid can be increased at an external position of the plating cell. Increasing the oxidation strength of the plating liquid compensates for the depletion of molecular oxygen in block 102 when the oxygen concentration in the plating liquid is reduced. In some embodiments, increasing the oxidation strength of the plating liquid may be performed in a reservoir or may be performed at various locations in the plating system. The reservoir is also referred to herein as an oxidation station. The degree to which the oxidation strength of the plating solution is increased may depend on the plating solution flow rate, the plating current used to deposit the metal on the wafer substrate, and the plating solution volume. Increasing the oxidation strength of the plating liquid can be performed actively or passively. Examples of oxidizing agents that can be used to increase the oxidation strength include oxygen, purified oxygen, ozone, hydrogen peroxide, nitrous oxide, and various other conventional oxidizing agents that do not interfere with electroplating. The selected oxidizing agent can promote formation or maintain the formation of the active plating additive. The selected oxidizing agent may be highly soluble in the plating solution. Another example of an oxidizing agent includes an oxidizing anion or a salt or another compound containing a cation such as a ferric ion (Fe (III)) or a cerium ion (Ce (IV)).

In some embodiments, increasing the oxidation strength of the plating liquid is performed passively. In a passive process, the plating liquid may be exposed to air. Oxygen gas can diffuse into the plating solution to reoxidize the solution. For example, the reservoir can maintain the amount of plating liquid in contact with air, for example under ambient conditions. Oxygen and nitrogen from the air will gradually diffuse into the plating solution while the plating solution will passively increase the oxidation intensity of the solution while remaining in the reservoir. In some embodiments, if re-introduction of nitrogen into the plating liquid is undesirable, oxygen may be added to the plating liquid by exposing the plating liquid to oxygen, purified oxygen, or ozone. In some embodiments, oxygen can be added to the plating liquid by exposing the plating liquid to nitrous oxide. For example, the oxygen concentration of the environment in the reservoir can be about 2 ppm to 5 ppm. The concentration of oxygen in the plating solution may be about 1 ppm or more or about 2 ppm to 5 ppm after increasing the oxidation strength of the plating solution.

In another embodiment, increasing the oxidation strength of the plating liquid may be actively performed. The active process implies that an increase in the oxidation strength of the plating liquid occurs at a faster rate than that performed by passive processing, i.e., by contacting a certain amount of the plating liquid with air or another ambient condition. The active process may include an apparatus that promotes an increase in the oxidation intensity of the plating liquid.

Actively increasing the oxidation strength of the plating liquid may be performed at a storage or another location downstream from the point at which the oxygen concentration in the plating liquid is reduced. An oxidant (including air) may be introduced into the plating solution by any suitable device. For example, when the oxidizing agent is a gas, the oxidizing agent can be introduced by bubbling the gas into the plating liquid through a suitable foaming device located in the reservoir or at another position in the plating system. In another example, increasing the oxidation strength of the plating liquid can be accomplished by passing the plating liquid over a wicking material, rib, or other large surface area structure to increase the air or gas contact area of the plating liquid have. If the oxidant is a liquid, it can be introduced by adding the liquid to the plating liquid.

Experiments were performed to characterize the filling performance of the plating solution, the stability of the additive to the plating solution, and the effect of degassing on the polarization persistence of the plating solution for a prolonged period of electroplating (i.e., 1 to 320 hours) in the same plating solution Respectively. Experiments have shown that by reducing the concentration of oxygen in the plating solution to 2 ppm, the stability of the promoter, inhibitor and leveler agent to the plating solution is significantly improved, the fill performance is slightly improved, and the polarization of the plating solution Became more constant and more negative than 500 mV at 10 mA / cm ² , and the byproduct generation was reduced as compared with the plating solution having oxygen concentration from the surrounding environment.

Another experiment was conducted to characterize the filling performance, the degree of polarization, and the concentration of the promoter remaining in the plating solution after 30 hours from plating with the plating solution. This experiment was carried out using several plating solutions with different oxygen concentrations. As the oxygen concentration was reduced to a very low level, the promoter stability was continuously improved (i. E. From oxygen concentration from the ambient environment to oxygen concentration of 10 ppb). At the same time, as the oxygen concentration dropped below 1 ppm, the polarization strength of the plating solution began to decrease. The filling performance declined somewhat with respect to the plating solution having the oxygen concentration from the surrounding environment. This is because the accelerator concentration (e.g., SPS concentration) is too low to optimize the filling performance. Filling performance was shown to be improved for 1 ppm and 0.5 ppm oxygen concentration plating solutions because the accelerator stability is such that the concentration of the promoter in the plating solution is close to the starting level. Even at lower oxygen concentrations (i.e., less than 0.5 ppm), the filler performance significantly declined, even though the promoter stability was excellent. This is because the MPS by-product is stabilized in the bath at too high a concentration, resulting in polarization loss because MPS is a more potent catalyst for copper plating than SPS.

Device

Generally, a suitable apparatus will include a plating cell that uses a plating solution during electroplating and a plating solution circulation loop that maintains and recirculates the plating solution when the plating solution is not present in the plating cell. The plating liquid circulation loop may also include another element such as a filter, reservoir, pump, and / or degasser.

2A shows an example of a schematic diagram of an apparatus designed or constructed to implement the method described in the present invention. Apparatus 200 includes a plating cell 205 for plating a metal onto a wafer substrate using a plating solution; A degassing device (210) configured to remove gas from the plating liquid prior to transferring the plating liquid to the plating cell; And a reservoir (215) located between the plating cell (205) and the degassing device (210) and configured to facilitate increasing the oxidation intensity of the plating liquid. The arrows in relation to the apparatus 200 represent the flow of plating liquid in the apparatus. That is, when the apparatus 200 is in operation, the plating liquid may flow from the reservoir 215 to the degassing apparatus 210, to the plating cell 205, and then back to the reservoir 215. The plating liquid may flow from the plating cell 205 to the reservoir 215 by gravity, for example. A pump, such as a pump 220, may also pump the plating liquid through the components of the apparatus 200. The plating liquid passes through the filter 230 before entering the plating cell 205. The apparatus 200 may further include several valves, vacuum pumps, additional filters, and other hardware (not shown).

Before the plating liquid enters the plating cell 205 from the plating liquid reservoir 215, the plating liquid passes through the degassing apparatus 210. The degassing apparatus 210 can be connected to the vacuum pump 225 to degas the plating liquid. The degassing apparatus may be referred to as a degasser or a contactor. Degassing apparatus 210 removes one or more dissolved gases (e.g., both molecular oxygen and molecular nitrogen) from the plating liquid. In some embodiments, the degassing apparatus is a membrane contact degasser. Examples of commercially available degasser devices include Liquid-Cel ( ^TM ) from Membrana (Charlotte, NC) and pHasor ( ^TM ) from Entegris (Chaska, MN). The degassing apparatus can be used, for example, to adjust the plating solution flow rate, the degree of vacuum at both ends to the extent that the vacuum is applied by the exposed area and nature of the semi-permeable membrane applied to the degassing apparatus, It is possible to remove the dissolved gas. Typical membranes used in degassing systems allow flow of molecular gases but do not permit the flow of larger molecules or solutions that can not wet the membrane.

The reservoir 215 provides for the active or passive introduction of oxidant to the plating liquid. Passive introduction includes exposure of the plating solution to air, for example. Active introduction may include the use of blowers, large surface area air contact structures, and the like.

Figure 2B shows a schematic example of a reservoir. The reservoir 215 contains a plating liquid 260. The reservoir 215 includes a plating liquid inlet port 252, a plating liquid outlet port 254, a gas inlet port 256, and a gas outlet port 258. The reservoir can include a membrane, fiber, rib, coil, or other large surface area structure (not shown). The plating liquid 260 flows over the large surface structure to expose a large surface area of the plating liquid to the gas. The structure in the reservoir can be made of, for example, plastic (e.g., polypropylene) or metal. While the plating liquid passes over the top of the structure, the plating liquid may also contact a gas flow (e.g., an oxygen flow or another oxygen-containing gas flow) from the gas inlet port 256 to facilitate re-oxidation of the plating liquid. The design of the reservoir can, for example, use features commonly found in evaporative coolers.

Therefore, the plating liquid in the plating apparatus 200 may have a low gas concentration (for example, when degassed) in the plating cell 205. [ However, at a location outside the plating cell, the plating liquid may be sufficiently oxidized to convert the equilibrium state of the additive to the plating liquid into a desired state (e.g., disulfide in contrast to mercaptan).

In some embodiments, the oxygen concentration can be maintained at a different location in the device 200 or at a particular level in the station when the device 200 is operating. For example, the apparatus can be designed and operated in such a manner that the oxygen concentration in the plating liquid is within a certain range at various positions or stages in the apparatus. In one embodiment, the concentration of molecular oxygen in the plating cell is maintained at a level of about 0.1 ppm to 1 ppm, and the concentration of molecular oxygen at a downstream location (e.g., in the reservoir) from the plating cell is about 2 ppm to 5 ppm Respectively.

The method of controlling the concentration of oxygen in the plating liquid includes the steps of (1) placing a degassing apparatus or reservoir at a specific position in the apparatus, (2) introducing an inlet or a dosing port for introducing oxygen or oxidizing agent into the apparatus , And / or (3) controlling the fluid dynamics of the plating liquid flow passing through the loop. With respect to the last possibility, the pump can be controlled, for example, in such a way as to achieve the desired level of degassing in the degassing apparatus.

In some embodiments, the concentration of oxygen (or another oxidizing agent or gas) is monitored at one or more (or more than one) locations within the apparatus 200. In one example, the apparatus can include an oxygen monitor in the reservoir, in the plating cell, and / or in another location in the plating solution circulation loop of the apparatus. For example, on-line oxygen monitoring can be performed using In-Situ, Inc. For example, commercially available oxygen probers such as those manufactured by F. Collins, CO. In another example, for example, YSI, Inc. A hand-held oxygen meter, such as a commercially available meter manufactured by Yellow Springs, OH, may be used.

Another aspect of the disclosed embodiments is a device equipped with a controller to accomplish the described method. A suitable apparatus includes hardware and a system controller having instructions for a control process operation to accomplish a process operation in accordance with the disclosed embodiments. The controller may operate with various inputs, including user inputs or sensed inputs from an oxygen monitor at one or more locations within the device, for example. In response to the associated input, the controller performs a control command to cause the device to operate in a particular manner. For example, the controller can adjust the pumping level, active oxidation, or other controllable characteristics of the device to adjust the concentration of oxygen to a specifically defined numerical range within the depot, or to a different defined numerical range within the electroplating cell Can be adjusted or maintained. In this regard, the controller may be configured to operate the pump of the apparatus, for example, at a level that maintains the oxygen concentration in the reservoir (or at some other point downstream from the electroplating cell in the recirculation loop) from about 2 pm to 5 ppm . The system controller will typically include one or more memory devices and one or more processors configured to perform the instructions and to perform the method in accordance with the disclosed embodiments. A machine-readable medium containing instructions for controlling a process operation in accordance with the disclosed embodiments may be coupled with the system controller.

3 shows an example of a schematic diagram of an electronic filling system 300. In Fig. The electronic filling system 300 includes three individual electronic filling modules 302, 304, and 306. The electronic filling system 300 also includes three separate post electronic filling modules (PEM) 312, 314, and 316 configured for various process operations. The modules 312, 314 and 316 are then processed with any one of the electronic filling modules 302, 304, and 306 to perform functions such as edge bevel removal, backside etching, and pickling of wafers, respectively Lt; RTI ID = 0.0 > (PEM) < / RTI >

The electronic filling system 300 includes a central electron filling chamber 324. The central electron filling chamber 324 is a chamber that holds the chemical solution used as a plating solution in the electron filling module. The electronic filling system 300 also includes a supply system 326 that stores and delivers chemical additives for the plating liquid. The chemical dilution module 322 may, for example, store and mix the chemical solvent to be used as the etchant in the PEM. The filtration and pumping unit 328 may filter the plating liquid for the central electron-filled chamber 324 and pump the plating liquid to the electronic filling module. The system may also include one degassing device or several degassing devices and one reservoir or multiple reservoirs (not shown) as described above. The plating liquid may pass through the degassing apparatus before it is pumped to the electroplating module. The plating liquid can pass through the reservoir after flowing through the electroplating module.

The system controller 330 provides the electronics and interface controls required to operate the electronic filling system 300. The system controller 330 generally includes one or more memory devices and one or more processors that perform instructions to configure the device to perform the method in accordance with the disclosed embodiments. A machine-readable medium containing instructions for controlling a process operation in accordance with the disclosed embodiments may be coupled with the system controller. The system controller 330 may also include a power source for the electronic charging system 300.

An example of an electroplating module and related components is shown in U.S. Patent Application No. 12 / 786,329 entitled " PULSE SEQUENCE FOR PLATING ON THIN SEED LAYERS "filed on May 24, 2010, which is incorporated by reference.

In operation, the hand-off tool 340 may select a wafer from a wafer cassette, such as cassette 342 or cassette 344, for example. The cassette 342 or 344 may be front opening unified pods (FOUPs). The FOUP is an enclosure designed to securely and securely hold the wafer in a controlled environment and to move the wafer for processing and measurement by a tool equipped with an appropriate load port and robotic handling system. The hand-off tool 340 captures the wafer using a vacuum applicator or some other attachment device.

The hand-off tool 340 may be associated with the annealing station 332, the cassette 342 or 344, the transfer station 350, or the aligner 348. From the transfer station 350, the hand-off tool 346 can access the wafer. The transfer station 350 may be a slot or place where the hand-off tools 340 and 346 exchange wafers without passing through the aligner 348. However, in some embodiments, the hand-off tool 346 may move the wafer past the aligner 348 to ensure that the wafer is properly aligned in the hand-off tool 346 for accurate delivery to the electronic fill module. . The hand-off tool 346 may also transfer the wafer to any of the electronic fill module 302, 304, or 306, or to any of the three individual modules 312, 314, and 316 configured for various process operations have.

For example, the hand-off tool 346 can transfer the wafer substrate to the electronic fill module 302 where a metal (e.g., copper) is plated on top of the wafer substrate in accordance with an embodiment of the present invention. After the electroplating operation is complete, the hand-off tool 346 removes the wafer substrate from the electronic fill module 302 and delivers it to any of the PEMs, such as the PEM 312, for example. The PEM can clean, clean and / or dry the wafer substrate. Thereafter, the hand-off tool 346 may move the wafer substrate to another one of the PEMs, such as, for example, the PEM 314. Here, the etchant solution provided by the chemical dilution module 322 can be used to etch unwanted metals (e.g., copper) from some areas of the wafer substrate (e.g., edge bevel areas and backside). The module 314 can also clean, clean, and / or dry the wafer substrate.

After the process at the electronic fill module and / or the PEM is completed, the hand-off tool 346 can retrieve the wafer from the module and return it to the cassette 342 or cassette 344. [ Post electronic fill annealing may be completed within the electronic fill system 300 or another tool. In one embodiment, the post-electron filled anneal is completed at one of the annealing stations 332. In another embodiment, a dedicated annealing system, such as a furnace, may be used. The cassettes may then be provided for further processing, for example, in another system, such as a chemical mechanical polishing system.

Suitable semiconductor processing tools are Saber System and Saber System 3D Lite manufactured by Novellus Systems of San Jose, Calif., Slim cell system manufactured by Applied Materials of Santa Clara, CA or Semitool of Kalispell, MT Includes manufactured Raider tools.

Additional implementation

The above-described apparatus / method can be used in combination with a lithographic patterning tool or process for manufacturing or manufacturing, for example, semiconductor devices, displays, LEDs, solar panels, and the like. Generally, although not required, such tools / processes may be used or performed with known fabrication facilities. Lithographic patterning of a film generally includes some or all of the following steps, each of which can use a number of possible tools: (1) using a spin-on or spray-on tool to separate the working material, Applying a photoresist to the substrate; (2) curing the photoresist using a hot plate or furnace or UV curing tool; (3) exposing the photoresist to visible light, UV, or x-rays using a tool such as a wafer stepper; (4) developing the resist to selectively remove the resist, and thereby patterning the resist using a tool such as a wet bench; (5) transferring the resist pattern to a lower film or working material using a drying or plasma-assisted etching tool; And (6) removing the resist using a tool such as a RF or microwave plasma resist stripper.

It should be noted that there are various alternative ways of implementing the method and apparatus of the present invention. Accordingly, the appended claims are intended to cover all such alternatives, modifications, substitutions, and equivalents as fall within the true spirit and scope of the embodiments of the present invention.

Claims (22)

(a) reducing the oxygen concentration of the plating solution, wherein the plating solution comprises a promoter of less than 100 parts per million (ppm), reducing the oxygen concentration of the plating solution;
(b) bringing the wafer substrate into contact with the plating liquid in the plating cell, wherein the oxygen concentration of the plating liquid in the plating cell is 1 ppm or less;
(c) electroplating a metal onto the wafer substrate using the plating solution in the plating cell, wherein the electroplating is performed in the plating cell by a conversion of the promoter into a less oxidized promoter species causing a net conversion in the first layer; And
(d) increasing the oxidation intensity of the plating liquid outside the plating cell, wherein the increased oxidation intensity is a net re-conversion from the less oxidized promoter species to the accelerator outside the plating cell, And increasing the oxidation intensity. The method according to claim 1,
Further comprising repeating steps (a) and (d), wherein the plating solution flows through the plating cell during step (c). The method according to claim 1,
Further comprising the step of supplying the plating solution from the plating reservoir to the plating cell, wherein the oxygen concentration of the plating solution in the plating reservoir is greater than 1 ppm, and reducing the oxygen concentration of the plating solution comprises: / RTI > The method according to claim 1,
Wherein the metal is copper. The method according to claim 1,
Wherein the plating solution comprises copper ions at a concentration of 20 to 60 g / L. The method according to claim 1,
Wherein the promoter comprises a mercapto-containing species. The method according to claim 1,
Wherein step (d) comprises exposing the plating solution to a gas containing an oxidizing agent, wherein the gas is selected from the group consisting of air, oxygen, ozone, and nitrous oxide. The method according to claim 1,
Wherein the step (d) comprises exposing the plating solution to the gas containing the oxidizing agent by blowing the gas containing the oxidizing agent through the plating solution, wherein the gas is air, oxygen, ozone, and nitrous oxide ≪ / RTI > The method according to claim 1,
Wherein the step (d) comprises exposing the plating solution to the gas containing the oxidizing agent while increasing the gas contact area containing the oxidizing agent of the plating solution, wherein the gas is air, oxygen, ozone, and nitrous oxide ≪ / RTI > The method according to claim 1,
Wherein the step (d) increases the oxygen concentration of the plating solution to 1 ppm or more. The method according to claim 1,
Wherein said step (d) comprises mixing a liquid containing an oxidizing agent into said plating liquid. 12. The method of claim 11,
Wherein the liquid comprises hydrogen peroxide. The method according to claim 1,
Wherein step (a) is performed by a degassing apparatus. The method according to claim 1,
Wherein said step (a) is carried out by sparging said plating solution with helium or nitrogen. The method according to claim 1,
Wherein said step (a) improves the stability of said plating solution. The method according to claim 1,
Wherein said step (d) improves the filling characteristics of said plating liquid to fill said features onto said wafer substrate. The method according to claim 1,
Applying a photoresist to the wafer substrate;
Exposing the photoresist to light;
Patterning the photoresist and transferring the pattern to the wafer substrate; And
Further comprising selectively removing the photoresist from the wafer substrate. An apparatus for electroplating a metal,
(a) a plating cell configured to hold a plating liquid;
(b) a degassing apparatus connected to the plating cell and configured to remove oxygen from the plating liquid before the plating liquid flows into the plating cell; And
(c) an oxidation station connected to the plating cell and configured to increase the oxidation strength of the plating solution after the plating solution flows out of the plating cell; And
(d) a controller including program instructions for performing the process,
The process comprises:
(1) reducing the oxygen concentration of the plating liquid by using the degassing apparatus, wherein the plating liquid includes an accelerator of not more than 100 parts per million (ppm); reducing the oxygen concentration of the plating liquid;
(2) contacting the wafer substrate with the plating liquid in the plating cell, wherein the oxygen concentration of the plating liquid in the plating cell is not more than 1 ppm;
(3) electroplating a metal onto the wafer substrate using the plating solution in the plating cell, wherein the electroplating is performed in the plating cell to convert the promoter into a less oxidized promoter species Electroplating; And
(4) increasing the oxidation intensity of the plating liquid outside the plating cell using the oxidation station, wherein the increased oxidation intensity is greater than the conversion of the less oxidized promoter species to the promoter And increasing the intensity of the oxidation which results in an increase in the oxidation intensity. 19. The method of claim 18,
Wherein the degassing apparatus is connected to the oxidation station and the apparatus further comprises an electrolyte flow loop configured to circulate the plating liquid through the apparatus. 19. The method of claim 18,
Wherein the oxidation station is configured to increase the gas contact area of the plating liquid. 20. A system comprising a device and a stepper as claimed in claim 18. A non-transitory computer-readable medium comprising program instructions for controlling an apparatus comprising a system controller for performing a process,
The command
(a) a code for reducing an oxygen concentration of a plating solution, the plating solution comprising not more than 100 ppm of an accelerator;
(b) a code for bringing the wafer substrate into contact with the plating liquid in the plating cell, wherein the oxygen concentration of the plating liquid in the plating cell is 1 ppm or less;
(c) a code for electroplating a metal onto the wafer substrate using the plating solution in the plating cell, wherein the code for electroplating is selected from the group consisting of (i) the order of the promoter to the less oxidized promoter species in the plating cell, Said code causing a conversion; And
(d) a code for increasing the oxidation strength of the plating liquid outside the plating cell, wherein the increased oxidation intensity causes a net changeover from the less oxidized promoter species to the promoter again outside the plating cell, Lt; RTI ID = 0.0 > computer-readable < / RTI > medium.

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